Smoothness

Target Performance Objective: Percent of travel on the NHS meeting the pavement performance standards for good and acceptable ride. By 2008, increase the percentage of vehicle miles traveled on pavement with good ride quality to 58.5%, and increase the percentage of vehicle miles traveled on pavement with acceptable ride quality to 95%. The most recent reported value (2004) for good ride quality is 51.8% and for acceptable 90.6%.

Background: The Mobility Goal of the 1998 FHWA National Strategic Plan included a performance indicator to "increase the percentage of miles on the NHS that meet owner-agency managed pavement performance for acceptable ride quality to 93% within 10 years." Defined as International Roughness Index (IRI) less than or equal to 170 inches of roughness/mile.

In 2002, this indicator was changed to focus on roads with the highest traffic. The revised performance goal was to increase to 95% the amount of travel on the NHS with a reported IRI of 170 inches/mile (or less) by 2008. Additionally, a secondary performance goal was established which focused on increasing the amount of travel on roadways considered with good ride quality, a reported IRI of 95 inches/mile (or less).

In 2006, this goal was further modified to make good ride quality, NHS roads with the reported IRI of 95 inches/mile (or less), as the primary performance target and the secondary performance target, 170 inches/mile (or less).

To increase ride quality, an owner-agency needs to build the pavements better initially because pavements built smoother initially, last longer and continue to preserve existing pavement in good condition. Additionally, the data used to measure progress must be verified to ensure progress towards the goal is properly documented.